Kate if you are worried, the hospital dont mind checking it out. But I find that when its still early, you dont feel them all the time, because they are so mobile( lotsa room in there) and if they are pointing towards your spine you dont feel it as easy as there are not many nerves back there. Also when you have another little one to run after you would be having movements, but are not feeling them as you are distracted IYKWIM?
Have you tried lying down with a glass of ice water. I never felt the littlies move until afternoon, when twins resting, and I would sit down with my feet up and an icy drink ( it helps) then I would feel movements.
Thinking of you.